This invention related to an electric drive system suitable for supplying power to the propulsion of vehicles such as automobiles, trucks, boats, etc. Since in the present state of the battery art no practical battery can supply sufficient power on one charge for an adequate travel range for the types of vehicles named, it is necessary to incorporate a charging system primarily dependent upon a combustion engine. Such systems as a whole are not new but they have had extremely limited applicability for various reasons including costs, electrical control problems and the like.
There are numerous reasons in today's world where energy shortage and energy cost have become so significant to reevaluate the combination combustion engine-battery type propulsion system as certain combinations of these elements enable a system to offer unique advantages clearly superior to existing combustion engines or to existing battery powered systems or combinations thereof.
By way of example, an automobile engine of current design, operated at its most efficient speed, is expected to have an efficiency of 20 to 25 percent. Nevertheless, the average efficiency of the ordinary motor car is much less, being only on the order 2-5 percent, primarily because of poor compression ratios at low speed operation. The problem is how to avoid inefficiencies which are incident to the operating cycle rather than to the basic engine construction.